Indicating system for light signals



Oct. 29, 1929.

C. W. PRESCOTT INDICA'IING SYSTEM FOR LIGHT SIGNALS Filed Fb. 25. 1926 28heets-Sheet 1 OctL ZQ, 1929. c. w, PRESCOTT 1,733,977

INDICATING SYSTEM FOR LIGHT SIGNALS D Filed Feb. 23 1926 F|ca.3.- I 2 2 Sheets-She et 2 Patented Oct. 29, 1929 use CHARLES W. PRESCOTT, OF ROCHESTER, NEW YORK, ASSIGNOB TO GENERAL RAILWAY SIGNAL COMPANY, OF ROCHESTER, NEW YORK INDICATING SYSTEM FOR LIG'HT SIGNALS Application filed February 23, 1926*. Serial No. 90,062.

This invention relates to railway traflio controlling systems, and more particularly to a system'for controlling interlocking mechanism in accordance with the indicating conditions of light signals and protected by cross-protection and tower indicating means.

In the provision of light signals for rail way signaling purposes, difficulty has been experienced in obtaining a reliable indication in the tower as to the indicating condition or a wayside light signal, and difficulty has been experienced in providing proper protection against the display of a favorable trafic indicating condition possibly by the reason of false current due to a cross, ground, or the like, at a time when a conflicting route is set up; adequate means for indicating the condition of light signals by itself has, how ever, been disclosed in a general way in my prior application Serial No. 725,389 filed July 11, 1924.

The present invention relates more particularly to a more complete system of light signaling for railways, and the object of the present invention resides primarily in the provision of adequate indicating means at the tower for indicating the condition of a light signal, and to meansfor protecting the way side signals against'giving a false clear indi- 3O cation due to crosses, and the like, that is, the

giving of a proceed indication when such an indication is improper and dangerous. A

further object of the present invention, resides in the provisionof additional electrical checks and shunting contacts, so as to assure against a false signal indication; and further resides in the provision of automatic means for preventing a danger wayside signal lamp from being extinguished until a proceed wayside signal lamp is illuminated, and for causing the danger lamp to be illuminated if the proceed lamp is extinguished.

Other objects, purposes and characteristic features of the invention will appear asthe description of the several embodiments thereof progresses.

' In describing the invention in detail reference will be made to the accompanying drawing in which Fig. 1 shows a semi-automatic light signal Fleming valve type, this indication being system in which visual proceed and stop indications are given at the tower inresponse to the illumination of proceed signals and a stop signal respectively, by signal lamps of' the given over a single wire and by a polarized relay in response to the polarity of therecti fied current derived from the particular signal lamp illuminated at the time,and inwhich the lever is prevented from beingre'moved to the normal position when in the iridi eating position-unless the danger lamp'filament is incandescent;

Fig. 2 shows a system similar to that illustrated in Fig. 1, in which the provision for giving a proceed signal indication in the tower has been omitted, and in which the fail? ure of the circuit'of a proceed lamp at a time when such proceed lamp should be illuminated'automatically illuminates the danger lamp; f

Fig. 3 shows awholly automatic signal for automatic block signal territory, in which means areprovided whereby the failure of the circuit of a proceed lamp illuminates'the danger lamp when such proceed lamp should be illuminated; and i y Y Fig. 4 shows a semi-automatic interlocking system in which cross-protection is pro-1' vided by having the proceed relay checked against false energization thereof by crosses, this by having this relay in multiple with a repeatedly checked partial circuit including the cross-protection relay, so that the application of false current to the proceedrelay causes energy to be out off of the system, by the cross-protection relay. 1 V

Referring to Fig. 1, in which a'tralfic controlling system has been illustrated embodying certain features of the present invention shows a trackway comprising rails 1 divided by insulating joints 2 into blocks of which the block I and the adjacent ends of other blocks H and J only havebeen shown. The blocks I and J are provided with track relays T and '1 respectively at the entrance end thereof, and these blocks are provided with the usual trackway source of energy such 'as batteries 3 illustrated at the exit ends of the blocks H and I. At the-entrance end of the 100 block I is located a semiautomatic stop-andstay interlocking light signal S; whereas the entrance end of the block J is provided with the automatic light signal S embodying certain features of the present invention. The signal S located at the entrance end of the block I and its control circuits are more specifically shown in the wiring diagram of Fig. 1; whereas the wiring arrangement for the signal S is shown in Fig. 3. The signal S in Fig. 1 includes lamp signal casings having colored lenses to give distinctive light signal indications corresponding to clear, caution and danger by colors such as green, yellow and red, as illustrated by the lamps G, Y and R. These lamps are of the Fleming valve type, each of which includes a filament F and an anode, or plate, P.

The signal S, as heretofore mentioned, is a Semi-automaticinterlocked light signal, and

I therefore is automatically controlled but has superimposed thereon manual control by suitable lever mechanism which is interlocked with conflicting lever controlling other signals, switches, olerails and the like, as is common practice in interlocking systems. In the particular arrangement shown the signal S is normally held at danger by contacts controlled by the lever Lin the interlocking tower, even though traffic conditions in the blocks I and J are favorable as illustrated in Fig. 1. With the block I and J unoccupied the energizing circuit for the line relay LR, including front contacts 5 and 6 of the relays T and T respectively, is closed so that the relay LR is energized.

Adjacent the signal S is located a main relay MR for controlling the same which relay in the particular arrangement illustrated comprises a polyphase or three-position electroresponsive device of the alternatin current induction type. The winding 8 of this relay MR is connected directly across the al ternating current mains 7 and 9 which derive their energy from the secondary winding of the transformer 4 so that one phase winding of the relay MR is always energized. The other winding 11 of the relay MR is normally shunted or short circuitd by the contacts 1213 of the lever L, so that it is very unlikely that energy will be supplied to the winding 11 of this relay accidentally. Suitable means (not shown) is preferably provided in connection with the winding 8 to effect the necessary phase displacement between the currents flowing in the winding 8 and ll to effect proper operation of the relay. lVith the relay MR de-energized, as it is when the lever L is in the normal position, the transformer connected to the filament F of the lamp R is energized through the following circuit:beg1nning at the line wire 7, leading from the transformer 4 wires 18 and 19, contactQO of the main relay MR, wire 21, pri mary winding of the transformer 22, wires 23 and 24, to the other line wire 9 connected to said transformer 4. Vith the filament F incandescent, and with an alternating current potential due to the portion 25 of the secondary winding of the transformer 22 impressed across the plate and the filament of the lamp R, a pulsating current due to the rectifying action of the Fleming valve flows in the following circuit :beginning at the filament of lamp R, portion 25 of the secondary winding of the transformer 22, wires 26, 27 and 28 winding of the indication relay IR, locked in the tower, wires 29 and 30, contacts 31 and 32 controlled by the lever L, wires 33 and 34, winding of the cross-protection relay CR, wire 35, contacts 36' and 37 of the cross-protection relay CR, wire 38 then through wires 9, 24, 23, and 39 to the plate P of the lamp R.

. It will be noted that the current flowing in the circuit just traced is pulsating in character and flows from right to left through the indication relay IR, and current of this polarity causes contacts 43 and 44 of this relay to as some the left hand position thereby energizing the danger lamp 1".

It is thus noted that a reliable indication is given at the tower, which indication can only be present if the lamp R is energized. Because the indication current is uni-direc tional in character whereas the source of supply is alternating in character and the polarity of this uni-directional current is different from that of the indication current derivable from the lamps G and Y, as more clearly pointed out hereinafter.

Let us now assume that the lever L is moved to the reverse position, the extreme right hand position in Fig. 1. As the lever is moved toward the right the shunting contacts 12-13 and 31-32 are opened when the lever passes the half reverse position. As the lever reaches the full reverse position the left hand connection of the indication relay IR is connected directly to the line wire 9 of transformer 4; also, the winding '11 of the main relay MR, which is no longer shunted, is connected directly to the contacts 47 and 48 of the line relay LR. Under this condition the relay MR will assume the right hand and left hand position when the line relay LR is energized and de-energized, respectively; and further, the main relay MR is deenergized even though the lever L is in the reverse posit-ion if a track relay T is de-energized and the contacts 50 and 51 entirely disconnect the transformer 52 from the pole changing contacts of the line relay LR.

Let -us assume that the blocks I and J are not occupied, and with the lever L removed to the reverse position, the main relay MR is operated toward the right, so that the transformer 53 for supplying the filament F of the lamp G is energized through a circuit readily traced in the drawings. With this lamp G incandescent the potential due to the portion 53 ofthe transformer 53 impressedacross the plate and filament of the lamp G causes a current to flow from plate to filament in the followingcircuit:beginning at filament F, portion 53 of the transformer 58, wires 54, 55 and 24, wire 9, wire 56, contacts 5758 controlled by the lever L, wires 59 and 29, winding of the indication relay IR, wires 28, 27, 60 and 61 to the plate P of the lamp G. It will be noted that the indication current at this time flowed from left to right through the indicator relay IR, so that this relay'now assumes the right hand dotted position and energizes the indication lamp gy. In other words, therlamp G is connected to the indication circuit reversely from that of the lamp B, so that the rectified pulsating current flows through the indication relay IR in the reverse direction. If now, the block J becomes occupied, or the track relay T assumes its de-energized position for some other reason, the line relay LR is de-energized and the polarity of the alternating current applied to the winding 11 of the main relay MB is reversed, so that this relay assumes its left hand position and thereby illuminates the lamp Y instead of the lamp G. It is considered unnecessary to trace the energizing circuit for the lamp Y or, the indicationcircuit including the lamp Y and the indication relay IR since these circuits are substantially the same as those for the lamp G.

Let us now assume that the operator in the tower wishes to display a danger signal by the signal S for the purpose of stopping a train which might, endanger another train if the first mentionedtrain passed the signal S and in order for the operator to allow said another train to proceed he is required to put the lever L in its normal posit-ion, this in order to unlock another lever to permit said another train to proceed, all of which is accomplished by suitable mechanical or electrical interlocking mechanism between levers, as well known to those skilled in the art of interlocking. If the towerman moves the lever L toward the normal position, the indication magnet Ill l being de-energized the lever will be stopped when it reaches the half normal position in which posit-ion the contacts 5865 are closed, and the projecting pin 66 of the indication magnet 1M engages the shoulder 67 of the lever L. Since, however, this movement of the lever L causes'the main relay MB to assume its de-energized position the lamp R is presumably lighted, and if this lamp is not out of order an indication current will flow through the same circuit as heretofore traced when the lever L was in the normal position, but in the present instance the indication magnet 1M is connected in multiple across the indication relay IR through a circuit including the contacts 5865 as clearly shown in the drawings. The flow of this indication current energizes the indication magnet IM and permits the operator to complete the movement of his lover to the full normal position, in which position certain conflicting levers are unlocked, thus permitting the operator to allow certain trains moving on conflicting routes to proceed.

It will be pointed out at this time, that the, indication magnet IM is preferably responsive to uni-directional current only, so that it is very unlikely for the lever L to he accidentally unlocked due to alternating current flowing on account of crosses, or the like. Also, the cross-protection relay CR which is connected in series with the indication magnet, is one of the type in which its contacts are normally held closed by flux emanating from the permanent magnet PM forming the bottom yoke of this cross-protection relay, the top yoke 70 of this relay preferably comprising soft iron, and if indication current uni-directional in character flows through the coil in such a direction that the magnetic flux emanating from the permanent magnet PM is not shunted away from the yoke 70 this cross-protection relay is not actuated by indication current derived from lamp R.

-Since, under normal operating conditions only pulsating indication current of a polarity so as not to rob the yoke 70 of its permanent magnet flux is required to flow through this cross-protection relay CR this relay will not open in response thereto but if pulsating current of the reverse polarity or if alternating current should be applied to the crossprotection relay CR its contacts 36-437, l04ll, are opened, and the circuit for energizing the same will be broken at the contacts 3637. Also, in the event the cross-protection relay is operated the contacts 40 A are opened and cut energy off of the transformer 52, so that the relay MR cannot be energized, and a proceed indication cannot be given although the danger lamp R will not nar lam sif desired andthe roceed indication current may be supplied directly to the indication relay IR from a suitable source of current through contacts controlled direct; 1y by the main relay, MR, these contacts com pleting a circuit to apply the proper potential to the indication three position relay IE to cause it to assume a position corresponding to the position the relay MR is assuming at the time.

In systems, such as justdescribed, wherein a plurality of semi-automatic light signals are employed it may be desirable for the operator to be informed whenever a filament anywhere in the whole system burns out. To

illustrate applicants arrangement whereby this may be accomplished the indication relay IR of another signal lever has been shown. The bell ringing relay &6 is connected in an energizing circuit including the various normal and reverse contacts 45, 15 etc. of three position relays, or if polar neutral relays are used the neutral contacts thereof are connected in series. As indicated the bell a9 is sounded when the relay 46 is de-energized. By this arrangement if there is an indication relay anywhere in the system which is not energized either positively or negatively that is, is de-energized because there is no indication current flowing, the bell 19 is sounded. By this arrangement an audible signal is sounded when there is a dark or non-indicating multiple aspect color light signal anywhere in the interlocking plant.

Summing up the features of the form of the invention shown in Fig. 1, the arrangement shown provides means whereby the main relay is protected against false energization by crosses or the like by having one of its field coils shunted for all positions of the lever except the reverse position; provides means for cutting energy off of all equipment except the danger lamp when alternating current, or uni-directional current of the wrong polarity traverse the indication magnet and cross protection relay connected in series therewith, so that it is very unlikely for a proceedlamp to be illuminated when the lever is normal, also it is very unlikely for the lever to be unlocked due to false current at a time when the lamp R is not illuminated. Further the embodiment in Fig. 1 discloses reliable visual and audible indication means for informing the operator'as to the indicating conditions of the various multiple unit color light signals.

In Fig. 2 of the drawings has been shown a system which is in many respects the same as that shown in Fig. 1, and for this reason the portion shown in the dotted rectangle in Fig. 1, as well as the trackway apparatus, have been omitted. Since many of the elements of the system shown in Fig. 2 are the same as those shown in Fig. 1 such elements have been assigned like reference characters. The main difference of the disclosure in F 2 from that shown in Fig. 1 is that the indication circuit leading from the lamps G and Y to the indication relay IR has been omitted. Another feature resides in the provision of a danger relay DR which is energized when the main relay MB is energized providing that the particular lamp G or Y lighted for the particular position of the main relay MR has its filament intact and is lighted and is providing indication current through the danger relay DR. This circuit arrangement automatically substitutes the danger indication for a proceed indication if the filament of the proceed lamp fails.

Let us assume that the main relay MR as sumes its right hand position and the clear lamp G is illuminated for reasons given in connection with Fig. 1 of the drawings. With lamp Gr incandescent the portion 53 of the secondary winding of the transformer 53 supplies the necessary potential to cause rectified pulsating curent to flow through the following circuit :beginning at the filament F of the lamp G, the portions 53 of the transformer 53, wires 54, 55, 24, 9, 7 5 and 76, winding of the danger relay DR, wires 7 7 and 7 8, contact 7 9 to the main relay MR in either of its extreme positions, wires 80 and 81 back to the plate P of the lamp G. If now, for any-reason, the lamp G should fail to be illuminated, probably because its filament is burned out or an essential wire for energizing the same has been broken, indication current no longer will flow to the danger relay DR and this relay will assume its de-energized position. \Vith the danger relay DR ole-energized the following energizing circuit for the danger lamp R is completed :beginning at the wire 7 leading from transformer 4: wires 18 and 84 back contact 85 of the danger relay DR, wire 86 primary winding of'the transformer 22, wires 8'? and 88 and 24 back to the wire 9. With the danger lamp R incandescent the indication relay IR is energized'to a posit-ion to illuminate the indicating lamp 1", and if the lever L is moved to the half normal position the indication magnet TM is energized in a manner as already clearly described in conneetion with Fig. 1 of the drawings. In other words, the system shown in Fig. 2 is the same as that shown in Fig. 1 except that the indication current derivable from lamps G and Y is used for maintaining the danger lamp R cut oil, that is, the indication current from the lamp G or Y as the case may be, maintains the danger relay DR energized and in so doing cuts energy off of the red lamp R. Also, the indication relay IR is only con nected in the indication circuit leading from the danger lamp B, so that, this indication relay IR is only energized when the red lamp R is energized and gives a'visual indication at the tower under danger traffic conditions of the signal S only, and further indication current permits unlocking of the lever only if the danger lamp R is illuminated for reasons given in connection with the description of Fig. 1.

In Fig. 3 of the drawings have been illustrated the control circuits for the lamps of the three condition signal S shown in Fig. 1 for use in automatic signal territory. Under normal clear trafiie conditions the track relay T and the line relay LR are energized and thus illuminate the green lamp G through the following circuit :beginning at the secondary winding of the transformer 100, wire 101, front contact 102 of the track relay T ,'wire 103, front contact 104 of the line relay LE wire 105 primary winding of the transformer 106 connected to the filament of the lamp G wires 110, 107, 111 and 108 back to the secondary winding of the transformer 100. With the green lamp G incandescent, a proceed or clear traffic indication is given to a train moving from left to right in the direction of the arrow. Also, with the green lamp G incandescent an indication current will flow due to the potential of the portion 109 of the transformer 106 applied between the plate and the filament of the lamp G through the following circuit zbeginning at the filament of the lamp G portion 109 of the secondary winding of the transformer 106, wires 110, 107, 111 and 112, front contact 113, of the track relay T ,.wire 114, winding of the danger relay DB wires 115 and 116, from the plate to the filament of the lamp G The flow of this indication current which is uni-directional and pulsating in character, due to the rectifying effect of the lamp G of the Fleming valve type, causes the danger relay DB to be energized, thereby preventing the danger lamp R from being illuminated. If now, the filament ofthe green lamp G should burn out orshould the lamp be d-e-energized because one of the wires for supplying energy thereto should become broken, indication current will no longer flow to the danger relay DB and this relay assumes its de-energized position, in which position current is applied to the primary winding of the transformer 120 throught-he following circuit beginning at the secondary winding of the transformer 100, wires 101 and 121, back contact 122 of the danger relay DB wire 123 primary winding of the transformer 120, wires 124, 111 and 108 back to the secondary winding of the transformer 100. The net result is, that the failure of the green clear lamp causes the red danger lamp to be energized, this to avoid the engineer passing a dark signal which according to the rules governing train movements is to be taken as a danger signal. If now, the block in advance of the block J becomes occupied the line relay LE assumes its ole-energized posie tion whereas the track relay T remains en ergized. Under this condition of the relays T and LE the caution lamp'Y: is illuminated through the completion of the following circuitbeginning at the secondary winding of the transformer 100, wire 101, front contact 102 of the track'relay T wire 103, contact 104 of the line relay LE in its ole-energized position,'wire 126, primary winding of the transformer 127, wires 128, 107, 111 and 108 back to the secondary winding of the transformer 100. With the caution lamp Y il luminated a cautionwayside signal indication is given and the indication currentderived from this lamp Y flows through a circuitincluding the danger relay DB which circuit is substantially thesame as the indication circuit for the lamp G heretofore traced.

' That is, illumination of the caution lamp Y prevents the danger lamp R from being energized through the backcontact 122 of the danger'relay DR and failure of the filament of the lamp Y causes energization of the lamp R. I Let us now assume that the blockJ is occupied, or the track relay T is de-energized for some other reason, thus establishing danger traflic conditions.

Under this condition of the relays T and LE the danger relay DB is de-energized for two reasons. In the first place, no indication current can flow from the indication circuits including the lamps Y or G because these lamps are de-energized; further, the contact 113 contained in this indication circuit is open, so that, the danger relay DB is de-energized by reason of which the danger lamp S will be illuminated because the energizing circuit for its transformer 120, heretofore'traced, is completed. In other words, the three position light signal S in Fig. 3 is one wherein the clear and caution lamps are controlled directly by relays governed in accordance with trafiicconditions ahead and the danger lamp R thereof is controlled by a relay which responds to indication current derivedfromone or the other of the proceed lamps, so that the danger lamp is not extinguished until a proceed lamp is illuminated, thereby affording a more adverse signal indication in case one or the other of the proceed lamps Y and Gr is extinguished at a time when it should be illuminated.

In Fig. 4 has been illustrated another form of semi-automatic traffic controlling system, which is in many respectsthe same as the semi-automatic systems illustrated in Figs. 1 and 2, but is somewhat more complete and provides additional crossprotection features. The additional cross-protection features include the provision of a cross-protection relay, which is connected in multiple with the main relay MR at all times except when the lever L is in the reverse position so that falseenergization of main relay MR causes operatlon of the cross protection relay, i

The track relaysT and T the line relay LR, the main relayMR, theindication mag: net 1M, the lever L, the cross-protection relay OR, the danger relay DR and the signal lamps G, Y and R are substantially the same as those heretofore described, and the indication relays IE and IR are-constructed and function the same as'the indication relay IR heretofore described. The track relays T and T? may be assumed to be connected in track circuits having the same relation to the signal S in Fig. 4 as do the track relays of Fig. 1 have to the signal S insuch. Fig. 1.

' Under normal conditions when the lever L is in its normal position the fact that the relays T and LR are energized does not result in the application of current to either suitable transformer, wire 201, back contact 202 of the danger relay DR, wire 203, primary winding of the transformer 200, wires 204, 205, 206 and 207 to the common return wire C connected to the other side of said transformer. With the primary winding of the transformer 200 energized the filament of the danger signal lamp R is rendered incandescent thereby displaying a danger signal at the exit end of the block H (see Fig. 1). With the red lamp R illuminated the portion 209 of the secondary winding of the transformer 200 impresses a potential between. the heated filament and plate of the lamp R thereby causing the flow of indication current through the following circuit :beginning at the filament of the lamp R, portion 209 of the secondary winding of the transformer 200, wires 204, 205, 206, 207 and 212, contacts 36-37 of the cross-protection relay CR, wire 35 and winding of the cross-protection relay CR, wires 34 and 213, winding of theeindication relay 1R contacts 214215 controlled by the lever L, wires 216, 217, 226, 219 and 220 to the plate of the lamp R. With the filament of the lamp R incandescent, sufficient uni-directional current flows in the circuit just traced by reason of the rectifying valve action of the lamp R to cause the indication relay IR to assume its normal left hand position and illuminate the indicating lamp 1' located in the tower adjacent the lever L. It is desired to point out that the relay MB is connected in multiple with the indication relay 1R when the lever L is in its normal position as is obvious from the'circuit just traced, but by reason of the construction of this relay MR and the fact that the relay MB is one of the alternating current poly- ,phasetype, the application of this pulsating uni-directional current will not cause the main relay MR to assume its energized position.

It should be noted that if the lever L is moved to the half normal position no circuit changes take place except that the indication magnet TM is connected in multiple with the indication relay IE and if the lever is moved from the reverse to the half-normal or indicating position, for the purpose of finally moving it to its normal position to unlock conflicting levers, that indication current will flow from thelamp B through the circuit just traced, which current when the lever is in the half normal position causes the indication magnet TM in multiple with the indication relay IE to be energized and the lever to be unlocked, thus permitting the operator to move the lever to the normal position, thereby unlocking the conflicting levers in a. manner heretofore described. Let us assume, however, that when the lever is thus moved from the reverse to the half normal or indicating position, that the lamp R is not illuminated, possibly because its filament is burned out, or the like. If this is the case, no indication is received from lamp 9" or through IM and the operator is unable to complete the movement of his lever to the normal position, and therefore is unable to unlock the levers of conflicting trafiic controlling devices.

Let us now assume, that the lever L assumes its normal position, and a false or unauthorized connection, due to a cross, or the like, is made with the wire 234 connected to the source B positioned at contact finger 40 of relay CR to the control and indication wire 226, and still'the main relay MR will not assume the energized position because the presence of this unauthorized connection also causes alternating current to flow through the winding of the cross-protection relay OR the wire 212 and to the other terminal C of this source of energy. The flow of this alternating current through the cross-protection relay CR causes the cross-protection relay CR to open its contacts 40, 41 thereby disconnecting the common wire 239 leading from the B side of the alternating current source so that no further flow of alternating current is pos sible through the relay MR. It should be noted that the partial circuit just mentioned, through which current is permitted to temporarily flow when a false or unauthorized connection is made to the wire 226 leading to themain relay MB, is checked each time that an indication is received by the indication relay 1R in that the indication current must flow through it, so that, the integrity of this circuit is'assured and the cross-protection relay OR is assured to be energized by alternating current resulting from such a cross, and thus cause the contacts 36-37 and contacts 4041 to open. The opening of contacts 4041 entirely cutoff the source of alternating current used for feeding the proceed transformers 230 and 232 whereas the transformer 200 still has a source of alternating current available, as clearly shown.

Thus far, in connection with the description of Fig. 4 of the drawings, the lever L has been assumed to be in the normal danger position or in the half normal indication posi tion. a

Let us now assume that the operator moves the lever L to the reverse or. proceed position, and that the track relays T and T and therefore the line relayLR are energized. Under this condition the main relay MB is energized through a circuit which may be traced as followsz-beginning at the termi-.

nal B, contacts 22322 l controlled by the lever L, wire 225 control and indication wire 226, winding of the main relay MR,.wires 205, 206, 207 to common return wire G connected to the other side of said source of alternating current. With this circuit completed the main relay l iR assumes its energized position and since traffic conditions are assumed to be favorable, current is applied tothe primary winding of the transformer 230 through the following circuit :beginning at the terminal B of said alternating current source contacts 40-41 of the cross-protection relay wire 229, front contact 231 of the track relay T, wire 232, front contact of the line relay LR, wire 234, contacts 235236 controlled by the lever L, wires 237 and 238, front contacts 239 of the main relay lv R, wire 240, primary winding of the transformer 230, wires 241 and 242, front contact 243 of the main relay MR, wires 24A, 245, 246, 206 and 207 to the common return wire 0 connected to the other terminal of said alternating current source. With this circuit completed the filament of the lamp G" is rendered incandescent and its incandescency causes an indication current to flow through the indication relay 13 through the following circuit beginning at the filament of the lamp G,

the portion 247 of the secondary winding of the transformer 230, which produces the necessary potential to cause this indicating current to flow, wires 241 and 242, front contact 243 of the n ain relay MR, wii es 2%, 245, 246, 206 and 248, winding of the indication relay IR wires 24:9, 250 and 251 the plate of the lamp G and through the ionized ap between the plate and the filament of this lamp. This uni-directional pulsating current flows in a direction in the circuit just traced so as to cause the indication relay IE to assume the ri ht hand dotted position, thereby energizing the proceed indication lamps gg located in the tower adjacent the lever L. There is also another indication circuit through which current rectified by the lamp G flows which energizes the danger relay DR, which circuit is readily traced in the drawings, this relay DR being connected in multiple with the indication relay IR through a partial circuit including front'cohtact 228 of relay 7 With the dang r relay DR energized current is cut oil of the transformer 200 so that the dangei lamp R is extinguished. It should, however, be noted that failure of the lamp G, possibly because its filament is burned out, causes the flow of indication current to cease and'causes the relay DR to assume its de-energized position, thereby illuminating the danger lamp E. This illumination of the danger lamp R, however, does not cause the indication lamp 7' in the tower to be illuminated because the lever L is in the reverse position and theindication relay IE is disconnected from the indication circuit, but de-energization of the indication relay 1R gives the necessary information to the operator.

If the lever L is in the reversed position, as

has been assumed, and there is a train in the block containing the track relay T the line relay LR assumes its 'de-energized position the lam Y or an essential circuit connection P a 7 leading to this lamp, causes the danger relay DR to be de-energize'd and in turn causes the danger lamp It to be illuminated.

t should be noted, that-the primary windings of the transformers 230 and 232 are short circuited by the contacts 239 and 253 when the relay MB is in its de-energized condition, and that the wires 237 and 254: are connected together and to the common return wireC by back contacts 255'an-d 256 through the following partial circuit: tacts 255 and 256 of the main relay MR, wires 257, 219, 226, 217 and 216, contacts 214215, winding of the indication relay 1R wire 213,

winding of the cross-protection relay CR,

Wire 35, contacts 36-37 of the cross-protection relay CE, wire 208 to common return wire C. 'The flow of current in the partial circuit just traceddue tofalse 0r unauthorized connection to the wires 237 or 254 or any wires associated therewith when the lever is in the normalposition causes the cross-protection relay CR to disconnect the main wire 239 from the terminal B; also, if the main relay MR should assume its de-energized position by reason of a break in its energizing circuit at a time when the lever is'in its reverse position the application of current to the wires 237 or 254 through contacts 231 and233 of the relays T and LR would cause the crossprotection relay CR to operate and disconnect the energy from the proceed portion of the system. Further, it should be noted that there is still another shunting circuit for the wires 237 and'254 which is closed under normal conditions, which includes the contacts 260- 261 and 262-263 in multiple and: from whence this shunting circuit comprising wires 264, 217, and 216, contacts 21l.215, winding of the indication relay 1R wire'2l3, winding of the indication relay 1R WlI8 213, Winding of the cross-protection relay CR,

contact 3637 of the cross-protection relay CR, Wire 212 to the common return wire.

beginning at the con-- or J0 It is thus noted that in the arrangement shown in Fig. 4 practically every possible electro-responsive device which might cause a false indication if energizeo is shunted at a time when it should not be energized, that a cross-protection circuit including-the crossprotection relay CR bridges the main relay MR under normal conditions, so that if current were applied to the main relay MR it would simultaneously be applied to the crossprotection relay CR which would cause this relay CR to disconnect the main connection leading to said source of alternating current, and that the partial cross-protection circuit just mentioned and including the control and indication wire 226 is checked each time an indication is received by the indication relay IE or the indication magnet IM.

Having thus shown various traffic controlling systems which include various features embodying the present invention in various combinations, it is desired to be understood that the specific circuit arrangements illustrated have been chosen for the purpose of illustrating the invention rather than showing the specific manner in which the invention is preferably applied, and that various changes, modifications and additions may be made to adapt the invention to the particular problems and railway systems encountered in practice, without departing from the spirit or scope of the invention or the idea of means underlying the same.

What I claim is e 1. In an interlocking system for railways employing light signals, the combination with a plurality of light signal units for each signal, a manually operable lever for controlling the illumination of said light signal units, automatic means for preventing said manually operable lever from effecting the display of a proceed indication when trafiic conditions are dangerous, and automatic means for illuminating a danger lamp underfavorable trafiic conditions it the filament of a proceed lamp which should be lighted at the time is not incandescent.

2. In an interlocking system for railways employing light si na s the combination with a plurality of light signal units a manually operable lever for controlling the illumination of said light signal units, automatic means for preventing salt manual y operable lever from eflfecting the display of a proceed indication when traffic condi ions are dangerous,and automatic means for indicating at the lever whether the filament ot a proceed lamp or a danger lamp is incandes cent. V

3. In an interlocking system for railways employing light signals, the combination with a plurality of light signal units a manually operable lever for controlling the illumination of said light signal units, automatic means for preventing said manually operable lever from effecting the display of a pro ceed indication when traflic conditions are dangerous, and automatic means for causing relay means to assume one position when a proceed lamp is illuminated and to assume a different position when a danger lamp is illuminated.

4. In a semiautomatic signal, the combination with a light signal having a plurality of light signal units, a lever having contacts for completing circuits for illuminating said signal units to give a proceed or a stop indication, automatic means for preventing a proceed indication from being given by movement of said lever when trailic conditions are adverse, and means for causing the flow of indication current of one characteristic if the filament of a light signal giving a favorable trailic indication is incandescent and for causing the flow of indication current of a different characteristic when a filament of a signal indicating adverse traflic conditions is incandescent.

5. In a semi-automatic signal, the combination with a light signal having a plurality of lig it signal units, a lever having contacts for completing circuits for illuminating said signal units to give a proceed or a stop indication, automatic means for preventing a pro ceed indication from being given by move ment of said lever when traiiic conditions are adverse, and means for causing a uni-directional current of one polarity to flow in an indication circuit when-a favorable tratlic indication is incandescent, and for causing a uni-directional current of opposite polarity to flow in an indication circuit when an ad verse traific indication is incandescent.

6. In a semi-automatic signal, the combination with a light signal having a plurality of light signal units each including an incandescent lamp having an anode therein, a lever having contacts for completing circuits for illuminating signal units to give a proceed or a stop indication, automatic means for preventing a proceed indication from being given by changing the position of said lever when traflic conditions'are adverse, and means for giving distinctive indications at the lever in response to a wayside proceed or a stop indication respectively, said means including two circuits in each of which is included the ionized gap between the filament and the' means, and the gap between filament and anode of a lamp of the signal disposed in its indication circuit to cause said relay means to assume different energized positions respectively in response to valve action of said lamps.

8. In an interlocking system, the combination with a lever for controlling a multiple aspect color light signal, a lamp of the Flemlng valve type for the stop signal unit of said light signal, a control relay which if energized extinguishes said stop signal unit a cross protection relay connected in multiple with said control relay when the lever is in the normal stop positionso as to'actuate said cross-protection relay if unauthorized current is accidentally applied to said control relay, said cross-protection relay if actuated cutting current off of the interlocking systems, whereby said control relay cannot be energized unless said cross protection relay is also energized, so long as said lever is in the normal stop position, and locking means for locking said lever against movement to the normal stop position effective unless the stop signal lamp is energized, said locking means being rendered'inefiective by current derived by valve action from said Fleming valve type stop signal lamp.

9. In an interlocking system for railways employing light signals, the combination with a plurality of light signal units for each signal a manually operable lever for controlling the illumination of the light signal units, automatic means for preventing said manually operable lever from effecting the display of a proceed indication when traflic conditions are dangerous, automatic means for illuminating a danger lamp under favorable trafiic conditions if the filament of a proceed lamp which should be lighted at the time is not incandescent, and automatic means for indicating at the lever whether the filament of a proceed lamp or a danger lamp is incandescent.

10. In an interlocking system, in combination, a lever for controlling a multiple aspect color light signal, a lamp of the Fleming valve type for the stop signal unit of said light signal, a control relay which is energized extinguishes said stop signal unit, a cross protection relay connected in multiple with said control relay when the lever is in the normal stop position so as to actuate said cross protection relay if unauthorized current is applied to said control relay, said cross protection relay if actuated cutting current off, of the interlocking system whereby unauthorized current cannot operate such control relay so long as said lever is in the normal stop position, and indicating means rendered active if the gap of said Fleming valve is ionized.

11. In an interlocking system, in combination, a lever for controlling a multiple aspect color light signal consisting of a plu-- rality of light emitting units emitting light.

beams of different color of which only one is active at one time, a control relay which if energized extinguishes the stop light unit of said light signal, and a cross protection relay connected in multiple With said control relay when said lever is in the normal stop position so as to actuate said cross protection relay if unauthorized current is applied to said control relay, said cross protection relay if actuated cutting current off of the interlocking system, whereby unauthorized current cannot operate said control relay so long as said lever is in the normal stop position.

' 12. In an interlocking system, in combination, a lever for controlling a multiple aspect color light signal consisting of a plu' rality of light emitting units emitting light beams of different color of which only one is active at one time, a control relay which if energized extinguishes the stop light unit of said light signal, a cross protection relay connected in multiple with said control relay when said lever isin the normal stop position so as to actuate said cross protection and indicating means near saidlever for apprising the operator of the indicating conditions of the units of said color light signal.

In testimony whereof I afiix my signature.

CHARLES W. PRESCOTT. 

